Chemically based vascular occlusion device deployment

ABSTRACT

A vascular occlusion device deployment system for placing an occlusion device at a preselected site within the vasculature of a patient. The deployment system employing a pusher having a lumen with an opening at the distal end of the pusher. A vascular occlusion device is connected to the distal end of the pusher by a portion that is removeably disposed within the opening. The portion of the occlusion device is forced out of the opening by an expandable reaction chamber, thereby deploying the occlusion device.

FIELD OF THE INVENTION

The present invention is related to deployment systems and methods foraccurately and rapidly deploying vascular occlusion devices at apreselected location within the vascular system of a patient, and moreparticularly, deployment approaches that utilize an expanding chemicalreaction chamber to facilitate rapid deployment of vascular occlusiondevices.

BACKGROUND OF THE INVENTION

The use of catheter delivery systems for positioning and deployingtherapeutic devices, such as dilation balloons, stents and emboliccoils, in the vasculature of the human body has become a standardprocedure for treating endovascular diseases. It has been found thatsuch devices are particularly useful in treating areas where traditionaloperational procedures are impossible or pose a great risk to thepatient, for example in the treatment of aneurysms in cranial bloodvessels. Due to the delicate tissue surrounding cranial blood vessels,especially for example brain tissue, it is very difficult and oftenrisky to perform surgical procedures to treat such a defect.Advancements in catheter deployment systems have provided an alternativetreatment in such cases. Some of the advantages of catheter deliverysystems are that they provide methods for treating blood vessels by anapproach that has been found to reduce the risk of trauma to thesurrounding tissue, and they also allow for treatment of blood vesselsthat in the past would have been considered inoperable.

Typically, these procedures involve inserting the distal end of adelivery catheter into the vasculature of a patient and guiding itthrough the vasculature to a predetermined delivery site. A vascularocclusion device, such as an embolic coil, is attached to the end of adelivery member which pushes the coil through the catheter and out ofthe distal end of the catheter into the delivery site. Some of theproblems that have been associated with these procedures relate to theaccuracy of coil placement. For example, the force of the coil exitingthe delivery catheter may cause the coil to over shoot the predeterminedsite or dislodge previously deployed coils. Also, once the coil ispushed out of the distal end of the catheter, the coil cannot beretracted and may migrate to an undesired location. Often, retrievingand repositioning the coil requires a separate procedure and has thepotential to expose the patient to additional risk.

In response to the above mentioned concerns, numerous devices andrelease mechanisms have been developed in an attempt to provide adeployment system which allows control of the occlusion device after thedevice has been delivered by the catheter and provides a rapid releaseor detachment mechanism to release the device once it is in place. Onesuch device is disclosed in Geremia et al. U.S. Pat. No. 5,108,407,which shows a fiber optic cable including a connector device mounted tothe end to the optic fiber. An embolic coil is attached to the connectordevice by a heat releasable adhesive. Laser light is transmitted throughthe fiber optic cable to increase the temperature of the connectordevice, which melts the adhesive and releases the embolic coil. Onedrawback to using this type of system is the potential risk of meltedadhesives contaminating the blood stream.

Another coil deployment system employs a pusher member having an emboliccoil attached to the pusher member by a connector fiber which is capableof being broken by heat, as disclosed in Gandhi et al. U.S. Pat. No.6,478,773. The pusher member of this arrangement includes an electricalresistance heating coil through which the connector fiber is passed.Electrical current is supplied to the heating coil by a power sourceconnected to the heating coil via wires extending through an internallumen of the pusher. The power source is activated to increase thetemperature of the heating coil which breaks the connector fiber. Onedrawback is that connecting the resistance heating coil to the powersource requires running multiple wires through the pusher member.Additionally, the electrical current traveling through the wires maycreate stray electromagnetic fields that interfere with other surgicaland monitoring equipment.

Yet another embolic coil positioning and delivery system is described inSaadat et al. U.S. Pat. No. 5,989,242, which discloses a catheter havinga shape memory alloy connector attached to the distal end of thecatheter. The connector includes a socket having a pair of spaced-apartfingers which are responsive to a change in temperature. The fingers arebent towards each other and hold a ball which is connected to an end ofan embolic coil. The connector absorbs laser light transmitted throughan optical cable and transmits the light into heat energy. The heatenergy raises the temperature of the connector and opens the fingers,thereby releasing the embolic coil. This type of ball and socketconnection is rigid and causes the catheter to be stiff, making itdifficult to guide the catheter through the vasculature of the body.This patent, and all other patents and references identified herein arehereby incorporated herein by reference.

Further, all of the above-identified delivery systems require electronicequipment powered by a power source. If the electronic equipment isdefective or the power source fails, for example a battery pack fails,the procedure may be prolonged while the equipment is repaired orreplaced. Prolonging the procedure may expose the patient to additionalrisk.

Therefore, a need remains for a rapid release vascular occlusiondeployment system or method that does not rely on electrical equipmentor a power supply, is simple to manufacture, flexible and easy to guidethrough the vasculature of the body, provides better control over theocclusion device, and reduces the possibility of interference with othersurgical and/or monitoring equipment.

SUMMARY OF INVENTION

The present invention embodies a deployment system and method foraccurately and rapidly deploying a vascular occlusion device at apreselected site within the vasculature of a patient. The deploymentsystem may employ an elongated flexible delivery catheter for guiding adeployment unit to the preselected site. The deployment unit includes adelivery tube or pusher that pushes and guides the vascular occlusiondevice, such as an embolic coil, through the delivery catheter to thepreselected site.

The pusher may include an internal lumen which has an opening at thedistal end of the pusher. The occlusion device includes a portion, suchas a headpiece, which is removeably disposed within the opening by afriction fit between the headpiece and the inner surface of the pusher.This arrangement maintains the connection between the occlusion deviceand the deployment unit until the desired deployment.

A reaction chamber is positioned with the lumen of the pusher. Thereaction chamber includes an expandable wall adjacent the headpiece ofthe occlusion device. Two reactants are mixed within the chamber tocreate a product that expands to a volume greater than the originalreactants. The product pushes against the expandable wall of the chamberwhich in turn contacts the headpiece. The force of the expandable wallagainst the headpiece overcomes the functional force between theheadpiece and the inner wall of the lumen, forcing the headpiece out ofthe opening, thereby deploying the vascular occlusion device.

Other aspects, objects and advantages of the present invention will beunderstood from the following description according to the preferredembodiments of the present invention, specifically including stated andunstated combinations of the various features which are describedherein, relevant information concerning which is shown in theaccompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

In describing the preferred embodiments of the present invention,reference will be made to the accompanying drawings, wherein:

FIG. 1 is an enlarged, partially sectioned view of the vascularocclusion device deployment system of a preferred embodiment of thepresent invention;

FIG. 2 is an enlarged partially sectioned view showing the deploymentunit of FIG. 1 prior to deployment of the occlusion device;

FIG. 3 is an enlarged partially sectioned view showing anotherembodiment of the deployment unit of the present invention;

FIG. 4 is a cross-sectional view of the reaction chamber of thedeployment unit shown in FIG. 3.

FIG. 5 is an enlarged partially sectioned view of deployment unit ofFIG. 2 with the piercing element piercing the walls of the reactionchamber;

FIG. 6 is an enlarged partially sectioned view of deployment unit ofFIG. 2 with the piercing element being retracted after piercing theintermediate wall;

FIG. 7 is an enlarged partially sectioned view of the deployment unit ofFIG. 2 shown just after deployment of the vascular occlusion device; and

FIG. 8 is an enlarged partially sectioned view of another embodiment ofthe deployment unit of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention, which may be embodied in variousforms. Therefore, specific details disclosed herein are not to beinterpreted as limiting, but merely as a basis for the claims and as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention in virtually any appropriate manner.

FIG. 1 generally illustrates a preferred embodiment of the vascularocclusion device deployment system of the present invention. Thedeployment system, generally designated at 10, includes an elongatedflexible guiding catheter 12 which is inserted into the vasculature of apatient and used to guide a deployment unit, generally designed 14, to apreselected site in a manner generally known in the art. The deploymentsystem 14 includes an elongated flexible pusher or delivery tube 16having a proximal end portion 18 and a distal end portion 20. Aninternal lumen 22 extends from the proximal end portion 18 to the distalend portion 20 of the pusher 16. A vascular occlusion device 24,generally illustrated as an embolic coil, is removeably disposed withinan opening 26 (which can be seen in FIG. 7) of the lumen 22 at thedistal end 20 of the pusher 16.

The lumen 22 includes a reaction chamber 28 located proximal the opening26 of the lumen. One embodiment of this reaction chamber 28 isillustrated in FIG. 2. In this embodiment, the reaction chamber isdefined by a proximal wall 30, a distal wall 32 and an inner surface 34of the pusher. The reaction chamber 28 typically has an axial lengthbetween about 3 millimeters and about 6 millimeters. An intermediatewall 36 is located between the proximal wall 30 and the distal wall 32to divide the reaction chamber 28 into a first chamber 38 and a secondchamber 40. Each of the chambers 38, 40 has an axial length preferablybetween about 1 millimeter and about 5 millimeters. The respectivechambers need not have identical axial lengths.

The proximal wall 30 and the intermediate wall 36 are comprised of apiercable membrane. The distal wall 32 is comprised of an elasticexpandable membrane. Preferably, the distal wall is a membrane made of asilicone elastomer having substantial flexibility and elasticity. Theother membranes also can be made of a silicone polymer. The materialsused in forming the proximal wall 30, distal wall 36 and intermediatewall 32 should be selected as not to significantly degrade while incontact with the reactant materials.

Typically, the respective membranes will have different Durometerhardness values. For example, the proximal wall 30 and the intermediatewall 36 preferably are made of a higher Durometer polymer than thedistal wall 32. Further, the membranes or walls 30, 32 and 36 of thisembodiment may be attached to the inner surface 34 of the pusher 16 byan adhesive, such as a silicone or cyanoacrylate adhesive, or by anyother suitable manner.

A first reactant 42 is housed within the first chamber 38 and a secondreactant 44 is housed within the second chamber 40. When the first andsecond reactants 42, 44 are mixed, they produce a product which has agreater volume than the combined volume of the first and secondreactants prior to mixing. The first and second reactants 42, 44 can beany reactants that produce a product having a greater volume than theoriginal compositions. Preferably, the first and second reactants may beany of the reactants disclosed in Cooke et al. WO 92/09651, herebyincorporated herein by reference, which produce a polycyanoacrylatefoam. In particular, the first reactant is preferably a mixture ofcyanoacrylate monomer and ethanol and the second reactant is preferablya mixture of ethanol and N,N-Dimethyl-p-toluidine. Other reactantmaterials, that when combined form a foam material with an increasedbulk volume relative to the reactants, such as precursors forpolyurethane foam are also suitable.

The delivery unit 14 also includes a piercing member 46, generallyillustrated as a mandrel. As illustrated in FIGS. 1 and 2, the piercingmember 46 includes a pointed tip 48 for piercing the proximal wall 30and the intermediate wall 36. Illustratively, the piercing member 46 maybe axially advanced and retracted through the lumen 22 by a controlcable 50 that is attached to the proximal end of the piercing member 46.A control handle 52 may be connected to the proximal end of the cable 50to facilitate such movement. Alternatively, the control cable 50 maytake the form of a rod, wire or tubular member with sufficientflexibility and pushability to navigate through lumen 22, as well as,controllably advance piercing member 46.

The illustrated vascular occlusion device 24 includes a portion orheadpiece 45 which is sized and shaped to be removeably disposed withinthe opening 26 at the distal end 20 of the pusher 16 so that a proximalend 47 of the headpiece 45 is adjacent the distal wall 32 of the chamber28. The headpiece 45 is preferably held in place by a friction fit withthe inner surface 34 of the pusher until the desired time of deployment,as will be discussed herein. Alternatively, the headpiece 45 may by heldin place by a relatively weak biocompatible adhesive or by any othersuitable manner.

As stated above, the occlusion device 24 may be an embolic coil whichmay take various forms and configurations, and may also be filled with afibrous material or may be coated with a beneficial substance, such as abiogel to promote clotting. Alternatively, the occlusion device also maybe any other occlusive device or approach known in the art such ashydrogels, foams, bioactive coils, braids, cables and hybrid devices.

A second embodiment of the delivery unit 14 is illustrated in FIGS. 3and 4. This embodiment is similar to the first embodiment except thatthe reaction chamber 51 comprises a unit that is separate from thepusher member, as shown in FIG. 4 and positioned within the pushermember. Illustratively, the reaction chamber 51 comprises a cylindricalhousing 52 having a sidewall 54, a proximal wall or membrane 56 and adistal wall or membrane 58. Similar to the first embodiment, thereaction chamber 51 is separated into two chambers 48, 50 by anintermediate wall or membrane 60. The proximal wall 56, the distal wall58 and the intermediate wall 60 are preferably of the same material andconstruction as described above in the previous embodiment.

The reaction chamber 51 is located proximal to the opening 26 of thelumen 22 so that the distal wall 58 of the reaction chamber 51 isadjacent the proximal end 47 of the headpiece 45 of the occlusion device24. As previously described, the materials used to form the reactionchamber should be relatively unaffected and not significantly degradewhen in contact with the reactant materials. The chamber 51 may be heldin place by an adhesive, such as a silicone or cyanoacrylate adhesive.

In operation, the catheter 12 is inserted into the vasculature of thepatient and positioned at a preselected location, typically inconjunction with other devices and professional procedures as generallyknown in the art. The delivery unit 14 is inserted into the catheter 12,and once the desired location is reached, the delivery unit 14 isadvanced and/or the catheter 12 is moved in a retrograde manner suchthat the delivery unit moves with respect to and within the catheteruntil the occlusion device 24 moves through the catheter 12 and out ofthe distal end of the catheter. During the procedure and before theocclusion device 24 has been deployed, if it is determined that thedistal end of the catheter 12 or the occlusion device 24 is not in thecorrect location, the occlusion device may be retrieved back into thedistal end of the catheter by retracting the delivery unit 14 proximallyor advancing the catheter distally. Once the occlusion device as beenretrieved, the catheter and/or the occlusion device may be repositioned.

When the occlusion device 24 is in the correct position, the piercingmember 46 may be advanced distally within the lumen 22 by manipulatingthe control handle 52 and cable 50. As illustrated in FIG. 5, thepiercing member 46 is advanced until the tip 48 pierces the proximalmembrane or wall 30 and the intermediate wall 36 of the chamber 28. Asillustrated in FIG. 6, piercing member 46 is slightly retracted to allowthe first reactant 42 and the second reactant 44 to mix. The proximalwall 30 is shown as a self-sealing wall which seals around the piercingelement 46 after the piercing element has pierced the proximal wall sothat the reactants are prevented from leaking out of the chamber 28. Thefirst and second reactants 42, 44 mix to form a product 43 which has agreater volume than the first and second reactants. The expanding volumeof the product 43 forces the lower durometer distal wall 32 of thereaction chamber to expand or stretch distally within the lumen,contacting the proximal end 47 of the headpiece 45 and forcing theheadpiece 45 out of the opening 26, thereby deploying the occlusiondevice, as illustrated in FIG. 7.

Another embodiment of the delivery unit 14 is illustrated in FIG. 8.Illustratively, the reaction chamber 60 is formed of a single unit andmay be attached within the lumen 22 at a location and in a manner asdescribed above. The reaction chamber 60 has a proximal wall 62 and adistal wall 64 which are comprised of polymers as described above.Alternatively, the reaction chamber 60 may be similar to that which isdescribed in FIG. 2 in that a portion of the reaction chamber 28 isdefined by the inner surface 34 of the pusher 16.

A dual-lumen dispending tube 66 extends into the reaction chamber 60preferably through the proximal wall 62. The dual-lumen dispending tube66 includes a first reactant 42 in a first lumen 68 and a secondreactant 44 in a second lumen 70. Each lumen 68, 70 preferably is closedat a distal location by a breakable seal 71, 72. The first and secondreactants 42, 44 are the same as described above in the previousembodiments and form a product which has a greater volume than theoriginal compositions. The dual-lumen dispensing tube 66 is preferablyplunger activated, but may also be activated by any other acceptablemethod known in the art.

In operation, the previously described procedure is employed to placethe occlusion device 24 at a preselected site within the vasculature ofthe patient. Once the occlusion device 24 is at the desired location,the dispensing tube 66 is activated, and the first reactant 42 and thesecond reactant 44 are dispensed out the dispensing tube 66 into thereaction chamber 60. The reactants 42, 44 mix together and react to forma product which has a larger volume than the original reactants. As theproduct expands, the product stretches the lower Durometer and/orflexible distal wall 64 of the reaction chamber 60 toward the opening 26of the pusher 16. The expanding distal wall 64 contacts the headpiece 45of the occlusion device 24, and forces headpiece 45 out of the opening26. Alternatively the dispensing tube 66 may include additional lumensof which one may serve as a vent lumen 74 to reaction chamber 60 toprevent the build up of fluid pressure within the reaction chamber whendispensing the reactants.

It will be understood that the embodiments of the present inventionwhich have been described are illustrative of some of the applicationsof the principles of the present invention. Numerous modifications maybe made by those skilled in the art without departing from the truespirit and scope of the invention, including those combinations offeatures that are individually disclosed or claimed herein.

1. A vascular occlusion deployment system, comprising: a deployment unitcomprising a pusher having a longitudinal axis, a proximal end portionand a distal end portion with a distal opening, said pusher including aninner wall at least partially defining a cavity proximal of said distalopening, said cavity having an expandable wall within the pusher andproximal the distal opening; a vascular occlusion device having aprotruding portion removeably disposed within the distal opening; afirst reactant and a second reactant located within the cavity proximalthe expandable wall of the cavity; and a frangible wall separating saidfirst and second reactants wherein said frangible wall is capable ofbeing breached to allow said first reactant and second reactant to mixforming a product that expands in the direction of the pusherlongitudinal axis and toward the distal opening, said expanding productcausing the expandable wall to expand in the direction of the pusherlongitudinal axis and toward the distal opening, whereby the expandablewall applies an axial pushing force to the protruding portion of thevascular occlusion device so that the protruding portion is removed fromthe distal opening, thereby deploying the vascular occlusion device; andan element for breaching the frangible wall.
 2. The deployment system ofclaim 1, wherein the element comprises a piercing mandrel.
 3. Thedeployment system of claim 1, wherein the first reactant comprises amixture of cyanoacrylate monomer and ethanol, and the second reactantcomprises a mixture of ethanol and N,N-Dimethyl-p-toluidine.
 4. Thedeployment system of claim 1, wherein the product comprises apolycyanoacrylate foam.
 5. The deployment system of claim 1, wherein thedistal wall comprises a silicone membrane.
 6. The deployment system ofclaim 1, wherein said cavity includes a breachable wall located proximalof the first and the second reactants.
 7. The deployment system of claim1, wherein the vascular occlusion device is an embolic coil.
 8. Thedeployment system of claim 1, wherein the protruding portion of thevascular occlusion device is friction fitted within the distal opening.9. A vascular occlusion device deployment system for deploying avascular occlusion device at a preselected site within the vasculatureof a patient, comprising: a deployment unit comprising a pusher having alongitudinal axis, a proximal end and a distal end portion, said pusherincluding an opening located in the distal end portion of the pusher,said opening configured to removably receive a portion of a vascularocclusion device; an expandable reaction chamber located within thepusher and including an expandable wall proximal of the opening in thedistal end of the pusher, said expandable wall is expandable in adirection of the pusher longitudinal axis and toward the distal end ofthe pusher so that the expandable wall applies an axial pushing force toremove the portion of the vascular occlusion device from the opening inthe distal end of the pusher, thereby deploying same; and wherein theexpandable reaction chamber includes an intermediate breachable wallwhich divides the reaction chamber into a first chamber and a secondchamber; a first reactant housed in the first chamber and a secondreactant housed in the second chamber; and a breaching member forbreaching the intermediate wall to allow said first and said secondreactants to mix together.
 10. The deployment system of claim 9, whereina portion of the expandable reaction chamber comprises an inner surfaceof the pusher.
 11. The deployment system of claim 9, wherein theexpandable reaction chamber comprises a housing attached to an innerwall of said pusher.
 12. The deployment system of claim 9, wherein thefirst reactant comprises a mixture of cyanoacrylate monomer and ethanol,and the second reactant comprises mixture of ethanol andN,N-Dimethyl-p-toluidine.
 13. The deployment system of claim 9, whereinthe expandable wall includes a distal wall which comprises a siliconemembrane that transmits the pushing force.
 14. A vascular occlusiondevice deployment system for deploying a vascular occlusion device at apreselected site within the vasculature of a patient, comprising: adeployment unit comprising a pusher having a longitudinal axis, aproximal end and a distal end portion, said pusher including an openinglocated in the distal end portion of the pusher, said opening configuredto removably receive a portion of a vascular occlusion device; anexpandable reaction chamber located within the pusher and including anexpandable wall proximal of the opening in the distal end of the pusher,said expandable wall is expandable in a direction of the pusherlongitudinal axis and toward the distal end of the pusher so that theexpandable wall applies an axial pushing force to remove the portion ofthe vascular occlusion device from the opening in the distal end of thepusher, thereby deploying same; and a first dispensing tube fordispensing a first reactant into the expandable reaction chamber and asecond dispensing tube for dispensing a second reactant into theexpandable reaction chamber.
 15. The deployment system of claim 14,wherein the first and second dispensing tubes comprise a dual lumendispensing tube.